Help with contrast/brightness on HDMI output
- This topic has 0 replies, 1 voice, and was last updated May 11, 2021 at 3:52 AM by .
Viewing 1 post (of 1 total)
Viewing 1 post (of 1 total)
- You must be logged in to reply to this topic.
NewHome › Forums › OSSC, OSSC Pro and DExx-vd isl › OSSC – Discussion and support › Help with contrast/brightness on HDMI output
Tagged: contrast adc
Hi folks,
I got an OSSC recently to help with a 1990 vintage computer, with 3 BNC RGB outputs which put out a Sync-on-green signal at 1280×1024 and 60Hz. Via a BNC-to-VGA cable, I can display the output just fine on (for example) a Dell 2009W LCD (native resolution 1680×1050, so some scaling artifacts). I am trying to convert the analog output to HDMI so I can use an HDMI capture system that I have.
I am noticing problems getting the HDMI conversion on the OSSC to have a nice, smooth brightness ramp. What I mean is, when I output a test pattern (e.g., a 20-bar color gradient of RGB, CMY and Gray), directly connecting the VGA to the Dell, I can see 18-20 of the 20 colors, with a little tweaking of brightness and contrast. However, when I view the DVI output from the OSSC on the same monitor, I can usually only discern about 12-14. The darker colors are all clipped to black, and the two or three brightest colors are indistinguishable.
I have tweaked the R/G/B offset and gain, and the Pre-ADC gain a lot, but don’t seem to be making much headway. The offsets look best at 0, and the gains anywhere between 25-75, and a pre-AGC gain around 5. Any ideas on what to try please?
I am using OSSC v1.6 with firmware 0.81a, with the VGA input from my 3BNC outputs, and the HDMI output to a DVI monitor (I do set the DVI mode) or HDMI capture device (AV.io HD; I do set the HDMI mode).
(Also, is there a way to get the OSSC to output a 1280×1024 digital signal? It is outputting a 1080p signal.)
Thanks!
Cookie | Duration | Description |
---|---|---|
_gat | 1 minute | This cookie is installed by Google Universal Analytics to restrain request rate and thus limit the collection of data on high traffic sites. |
Cookie | Duration | Description |
---|---|---|
__gads | 1 year 24 days | The __gads cookie, set by Google, is stored under DoubleClick domain and tracks the number of times users see an advert, measures the success of the campaign and calculates its revenue. This cookie can only be read from the domain they are set on and will not track any data while browsing through other sites. |
_ga | 2 years | The _ga cookie, installed by Google Analytics, calculates visitor, session and campaign data and also keeps track of site usage for the site's analytics report. The cookie stores information anonymously and assigns a randomly generated number to recognize unique visitors. |
_gid | 1 day | Installed by Google Analytics, _gid cookie stores information on how visitors use a website, while also creating an analytics report of the website's performance. Some of the data that are collected include the number of visitors, their source, and the pages they visit anonymously. |
Cookie | Duration | Description |
---|---|---|
IDE | 1 year 24 days | Google DoubleClick IDE cookies are used to store information about how the user uses the website to present them with relevant ads and according to the user profile. |
test_cookie | 15 minutes | The test_cookie is set by doubleclick.net and is used to determine if the user's browser supports cookies. |
Cookie | Duration | Description |
---|---|---|
ct_checked_emails | session | No description |
ct_has_scrolled | session | No description |
ct_mouse_moved | session | No description |
ct_screen_info | session | No description |
wordpress_apbct_antibot | session | No description |
wp_woocommerce_session_9cc3598a6315be16da4f85bb374cf6a5 | 2 days | No description |